US-backed fighters in northern Syria are preparing for a final offensive on neighborhoods still held by Islamic State (IS, formerly ISIS/ISIL) in Raqqa, a spokesman for the group said Monday. Mustafa Bali of the Kurdish-led Syrian Democratic Forces told AP that the battle is expected to last between seven to 10 days. The militants still have hundreds of fighters in the city, once their de facto capital. The forces launched an offensive against IS in Raqqa in early June, covered by US-led coalition’s airstrikes. The Kurdish-led group has captured 80 percent of the city. IS extremists are said to be still in control of parts of the Raqqa’s center and north.